2025 09 08 Work Session Packet

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PUBLIC WORKS 
 
d) Remove an outfall when the discharge from that outfall is terminated and 
does not result in discharge of pollutants from other outfalls except in 
accordance with permit limits. 
 
e) Modifications that replace an ineffective or infeasible BMP, or SCM which 
is specifically identified in the Stormwater Management Program along 
with an alternate BMP or SCM, may be made by the permittee at any 
time. A description of the replacement BMP or SCM shall be included in 
the subsequent Annual Report along with the following information: 
a. An analysis of why the former BMP was ineffective or infeasible; 
b. Expectations on the effectiveness of the replacement BMP or SCM; and 
c. An analysis, if applicable, of why the replacement BMP or SCM will ensure 
the optimization of equipment use. 
 
f) Addition of Facilities covered under this permit. 
 
 
The Department has identified since the most recent amendment of our current Stormwater 
Management Program , that TDEC has clarified its  stance on manufactured treatment devise, or MTDs , 
that necessitates a response and modification to the City’s permit. 
 
These changes specifically revolve around  total-suspended-solids, or TSS, treatment requirements as 
detailed in section 4.2.5.2 Permanent Stormwater Standards in the TDEC Small MS4 General Permit. The 
State recognizes only a select few  agencies methodology when benchmarking treatment devices. It has 
also clarified that attempting to daisy-chain or “treatment-train” certain MTDs, specifically hydrodynamic 
separator devices, or HDS units, does not  provide conjunctive TSS removal that meets the 80% removal 
requirement. Chapter 14 Section 14-130 Permanent Stormwater Management: Design and Construction 
Inspection details the City’s stance on this, and currently reads as follows: 
 
 
(4) Total suspended solids (TSS) removal rate shall be the City’s 
recognized metric for the reduction of pollutants in stormwater effluent. 
Design TSS removal rates for approved MTDs shall be established by a 3rd 
party verification or certification program recognized by the City such as 
those of NJDEP and WSDOE. 
 
 
 
 
 
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